But the much-hyped moon show that had been expected to accompany the impact turned out to be a flop—no billowing plumes of dust and ice visible through backyard telescopes or on NASA TV. The low-impact impact had one NASA expert musing that LCROSS may have struck a "dry hole."

Whether or not sky-watchers could see the LCROSS crashes, NASA insists they happened.

"I can certainly report that there was an impact," LCROSS principal investigator Anthony Colaprete said at a NASA press conference this morning. "We saw the impact and we saw the crater."

When the rocket crashed into the moon, though, cameras on LCROSS registered no discernable change in the crater—at least to the untrained eye.

"It was hard to tell what we saw there," said Michael Bicay, science director at NASA Ames Research Center in California, during live coverage on NASA TV.

A closer inspection of LCROSS impact images, though, has revealed a small white speck that scientists think is the debris thrown up by the first crash, but it will take time for scientists to determine whether it is evidence of water on the moon, NASA says. (See "There's Water on the Moon, Probes Confirm.")

"I'm not going to say anything about water or no water, but we got the data that we need" to address the question, LCROSS principal investigator Colaprete said.

The public excitement about LCROSS brought to mind the first Apollo moon landing, he said. "It's very evocative."

Did LCROSS Crash Into a "Dry Hole"?

Scientists say it could be days before data transmitted by LCROSS are fully analyzed. If no evidence for lunar water is found, that will be a significant finding in itself, Bicay of NASA's Ames center said.

It could mean water doesn't exist on the moon or that there's very little water or that it's only patchy.

"Like an old Texas wildcatter," Bicay said, "we may have hit a dry hole."